Year	US Dollars
1961	6.0646
1962	7.48325
1963	2.0248
1964	2.3186
1965	5.64976
1966	5.77792
1967	5.45075
1968	8.86211
1969	7.23313
1970	5.64792
1971	9.51678
1972	8.84979
1973	7.93186
1974	10.74496
1975	10.10936
1976	9.69704
1977	12.04909
1978	54.66994
1979	54.29208
1980	51.879
1981	63.02797
1982	73.92688
1983	76.63534
1984	73.0358
1985	72.38998
1986	75.34098
1987	68.79843
1988	78.48208
1989	109.08984
1990	113.53536
1991	68.00126
1992	50.48933
1993	42.69921
1994	48.77662
1995	45.63293
1996	24.6398
1997	29.85572
1998	8.96542
1999	-6.63644
2000	5.40922
2001	22.43463
2002	10.81401
2003	3.97959
2004	32.56352
2005	16.34376
2006	15.13202
2007	11.72063
2008	33.12344
2009	55.93592
2010	51.61133
2011	14.94081
2012	10.16734
2013	25.8156
2014	34.47244
2015	21.13837
2016	9.58007
2017	21.91658
2018	35.67421
2019	44.48475
2020	23.66301
2021	20.67055